Color printers as well as black and white printers use various consumables such as ink or toner to print text, images and the like. Each image is represented by a two dimensional array of pixels. Each pixel is printed by multiple circular shaped dots (or spots).
A color pixel can be represented in various manners. In the RGB space a pixel is represented by red green and blue components. In the CMY space a pixel is represented by cyan, magenta and yellow components. A CMYK pixel also includes a black component and a CMYKcm pixel also includes a light magenta component.
In an HLS space each pixel has a hue component, a luminance component and a saturation component. The hue represents the color of the pixel, the luminance represents the brightness of the pixel and the saturation represents the color intensity. Inter-space conversions from one color space to another are known in the art.
The cost of ink and toners is relatively high, and in many cases the cost of few consumable cartridges equals the cost of a printer. In order to reduce the cost of printing various ink consumption methods were suggested. A first method includes reducing the ink consumption as well as the printing quality by reducing the amount dots per pixel. Another method involved converting black regions in an image to gray regions. Yet a further method includes reducing dots at random. An additional method involved half toning. Some prior art methods for ink reduction are described in PCT patent application publication number WO03/049021 titled “Lowering the consumption of ink in computer printing” and in U.S. Pat. No. 5,872,896 of Li et al., titled “Continuous-tone ink reduction”. The patent and patent application are incorporated herein by reference.
There is a growing need to reduce consumable consumption.